1985 760Turbo Very Hard Starting/No Start

Post by **jonesg** » 16 Jan 2008, 15:47

I can sympathize as I have similar no go problems with my 740, having changed half the elecs and still no go, it can be frustrating.

A quick test for the fuel pressure regulator is to unplug the small vac hose, if the idle picks up the FPR is good.
Mine had fuel dripping out so it was obviously bad but a new one didn't fix the problem.

If you've got oil in your FPR vac line I might take alook at the oil trap, see if those pipes need cleaning and the throttle body too, get a new gasket.

I can always get mine running quickly by giving it a shot of ether down the vac line from the FPR, that'll fire it up.

If you get your sorted, post the answer so we can all learn.

Post by **sseir39** » 16 Jan 2008, 19:25

Have you checked or switched the power stage amplifier or radio suppresion relays? If you have not checked the brickboard.com and their FAQ you might do so. There is far more information there and it is good stuff. They have far more than a decade of information there and I have used and contributed to the information.

Don't give up, there is an answer somewhere.

Dick

turbo no/go · Post by **turbo no/go** » 17 Jan 2008, 12:37

I have inspected/cleaned the Ignition Amplifier(power stage), they are the same thing right?
I checked the connection and wiring.If I get spark fron ignition coil to plugwire then the amplifier works right??
It was one of the parts I replaced w/new within the last 18months, but I've heard a bad/dirty connection alone can cause trouble.
As far as the radio supression relay, I've seen some Volvos have them mounted on the coolant resovoir(square,usually black box similiar to my air mass meter)
All of my relays that I know about are behind the ashtray/radio assembly, and the only one fuel/ignition related is the fuel pump relay, which is new.
Do I have the radio surpression relay?(1985/2.3ltr.SOHC/turbo/intercooler/B230FT)Manufactured in Sweden 1984

Post by **sseir39** » 17 Jan 2008, 19:00

There usually are two. Black boxes as you describe, but can be mounted in different areas of the engine compartment. One is for turning on the aux. cooling fan and the other has to do with the fuel pump. Most folks just swap them to see it this makes the car run. If it does, then just get another used one.

Dick

turbo no/go · Post by **turbo no/go** » 18 Jan 2008, 10:30

This is a post that I found at brickboard concerning radio supression relays.
It would appear mine(85)is the only year that didn't use them.
__Radio Suppression Relay. [What is the Radio Suppression Relay and where is it?] The radio suppression relay (as it's called) is in actually a fuel injector relay. The pre 1986 injectors were supplied constant + power to one terminal and supplied a timed ground to the other terminal via the ECM. The constant + power used to come from the fuel pump/injection system relay. In 1986 Volvo decided to isolate the fuel injector circuit because of some radio interference created by the pulsing circuit. The solution was to energize a relay (the radio suppression relay) with the pump/system relay feed instead of using it to power the injectors directly. The radio suppression relay then supplies the + power to the injectors. The timed ground still comes from the ECM. The reason Alex can't find his radio suppression relay is because it's located on the other side of the engine compartment behind the power steering reservoir, (relay closest to the engine of the two relays mounted there Alex). For the most part the non-turbo engines had the radio suppression relay mounted on the right side (pass) of the engine compartment on or near the coolant reservoir as Alex mentioned. The turbo engines had the radio suppression relay mounted on the left side (drivers) of the engine compartment on or near the shock tower. Not set in stone just as a general rule. The radio suppression relay was used from 1986 until 1995 on almost all LH injected 4 cyl and V6 engines. There may be a couple of exceptions. The 5cyl and straight 6cyl engines do not use one. When it's bad or missing, the radio will work fine, but the engine will not run. Remember even though it's called a radio suppression relay it's function is to supply + power to the fuel injectors.
Problem diagnosis: If you suspect that your radio suppression relay is faulty (causing hot start problems, etc.) try switching the leads with the electric cooling fan relay if your car is so equipped. This relay is identical and in many car lines is located right next to the radio suppression FI relay. If your fan stops and your engine starts, then you've isolated the problem. See also Hot Start Problems.

turbo no/go · Post by **turbo no/go** » 18 Jan 2008, 12:32

Well it seems that the problem has been solved.Yesterday(Thurs.)
I was once again checking for spark.This time I pulled wire #1 off and held it an inch away from the top of the plug(instead of leaving the plug in the wire).I had a friend turning the ignition and as soon as the spark hit the plug the engine"bumped" for the first time...like it wanted to start.
Up until this point we had been trying to start it for about 15 minutes and it was being it's usual self, motor tuning over but no start.
I put the wire back on the plug and it started up strong and it has started first try every time since, even after sitting over night in below freezing temps.
Anyone have a clue what I did??
In order, right before it started I:
Took the wire off the coil to test for spark to rule out the ignition amplifier, there was spark.
I checked for spark from coil to distributor, there was spark
I pulled the wire from plug 1, hit the starter and it tried to actually start.
Then it started and hasn't hesitated to start once since, for the first time in 3 weeks.
Anyone know what may have happened to fix it?
Thanks for all the great advice along the way as well.

Post by **sseir39** » 18 Jan 2008, 12:53

Magic fingers?? Perhaps you moved some corrosion or made a slightly loose connection tight. Congradulations, regardless.

Dick

Ragman · Post by **Ragman** » 18 Jan 2008, 17:57

Just a guess, but you origally said your plugs were wet with fuel so I was thinking electrical/spark. When you changed your wire set were they by any chance Bosch wires. If so, some times the boot appears to seat on the plugs but due to the metal jacket surrounding the rubber boot it doesn't get pushed down far enough onto the plug head. Hence, no/ intermitent spark. Also if using these wire sets be sure to die-electric grease on the plug connection and the porcelain body to ensure easy removal. I've seen the wire be pulled out of the boot and ruin the wire. Personally, I use either Volvo / Bugicord wires or Magnecor 8mm wires. Congratulations on the fix.

turbo no/go · Post by **turbo no/go** » 19 Jan 2008, 16:20

Yeah, I'm definitely getting new plug wires, mine are not the originals but they're 3 years old and an 'el cheapo' brand .
In my 3 years of experience w/ this car, my first Volvo, I've found that when it comes time to replace a part, go w/Bosch-Volvo(i.e.'the most expensive') parts whenever possible.In the case of my water pump I went through 5 pumps (putting on..not fit/leak... taking off) before I found one that would fit.
In this case something was obviously wrong between wire and plug 1.
I had pulled the plugs 2-3 times over the past 3 weeks checking spark/fuel.
I always double checked that the cables were tight on the plug, but I guess there was still a bad connection.
I've also learned that the parts you overlook sometimes while trying to diagnose a problem(battery/plugs-wires/fuses-relays) can turn out to be the cause/root of the problem you're having.
Thanks for the advice, she's now running like a top...a 3500lb. top!

Post by **sseir39** » 19 Jan 2008, 16:33

I have been playing Volvo for 40 years and am still learnling. Just recently found that aftermarker coolant hoses are not as good as original equipment.

Happy your "top" is spinning!

Dick